1. Overview of Explosion Protection
1-3
TI 33Q01J30-01E
1.3
Classification of Explosion Protection
Equipment
Explosion protection equipment is classified as follows:
• Classification by to explosion protection constructions: what kind of method is taken for
explosion protection?
• Classification by hazardous area and explosive gas: in what kind of environment are they
used?
Classification by Explosion Protection Constructions
Type of explosion protection constructions are listed in the following table.
Table Type of explosion protection constructions
Type of explosion protection constructions
Abbreviation of standard
Flameproof enclosures
Type “d”
Pressurized enclosures
Type “p”
Increased safety
Type “e”
Oil immersion
Type “o”
Intrinsic safety
Type “i”
Powder filling
Type “q”
Encapsulation
Type “m”
Type of protection “n”
Type “n”
Non-Incendive
-
Classified roughly, explosion protection constructions include 4 types of the principle as below.
(1) It isolates the potentially explosive atmospheres from the place where sparks and high
temperature arise and prevents explosions. The constructions based on this principle
include Pressurized apparatus, Oil immersion, and Encapsulation.
(2) It keeps an explosion within the enclosure, if it is induced there. The constructions based on
this principle include Flame-proof enclosures.
(3) Even if sparks and heat is caused by an electric accident at the normal operation, it prevents
ignitions of potentially explosive atmospheres. The constructions based on this principle
include Increased safety, Type of protection “n”, Non-Incendive.
(4) If an electric accident such as short-circuit, ground fault, and burnout occurs, it doesn’t
ignite potentially explosive atmospheres, because of the system which the specific intrinsic
safety circuit is installed in. The constructions based on this principle include Intrinsic safety.
Intrinsic safety construction has the ia equipment, the ib equipment, and the ic equipment.
The ia equipment maintains its performance of explosion protection even if it has two
defects, it is able to react Zone 0 (Division 1). The ib equipment maintains its performance
of explosion protection even if it has one defect, it is able to react Zone 1 (Division 1). The
ic equipment maintains its performance of explosion protection under normal operating
conditions only, it is able to react Zone 2 (Division 2).
May 18, 2018-00
